1. Field of the Invention
The present invention relates to a human detection device that identifies a region of a person included in an image.
2. Description of the Background Art
Examples of techniques used to detect a person from an image taken by a camera include a neural network and pattern matching. It can be determined whether a person is present in a region set for detecting a person using such a technique.
Patent Document 1 discloses an object detecting system that detects a person from an image based on human symmetry.
In the object detecting system disclosed by Patent Document 1, a width of a person in an image is set depending on a longitudinal position in the image. The object detecting system evaluates horizontal symmetry in each pixel using a symmetry filter corresponding to the set width to generate a filter reaction image. The object detecting system subjects the filter reaction image to smoothing processing and thinning processing to obtain a segment from the filter reaction image. The object detecting system sets a rectangular region using a lower end of the segment as a reference and identifies whether the rectangular region is a candidate region including a pedestrian based on the vertical continuity and density of the segment in the rectangular region.
Patent Document 1: International Publication No. 2008/065729
As described above, whether a person is present in a set region in an image can be determined by a neural network or pattern matching. However, according to the above-described techniques, a human range in a candidate region cannot be identified even if the presence of a person in the candidate region is determined.
Furthermore, according to the above-described techniques, if the presence of a person is determined in a candidate region, a particular part (such as a torso and a leg) of the person included in the candidate region cannot be detected.
According to Patent Document 1, human bilateral symmetry is used to identify a candidate region in which a pedestrian is present. However, it is not presumed that the object detecting system according to Patent Document 1 would detect a particular human part similarly to a neural network.